The four tennis heavyweights were joined on the Manolo Santana show court at the Magic Box arena by women's world number one Serena Williams to pay tribute to Australian former player Drewett, who passed away aged 54 after suffering from Motor Neurone Disease.
"It's devastating news for not just us tennis players, but the tennis world," Djokovic said.
"He was a very brave man with the courage to stand up and try to change some things in our sport for the better," added the Serbian world number one.
"We remember him as a very calm, composed and intelligent man, who loved this sport with all his heart, while he was playing, coaching and then as the president of ATP."
Drewett, who reached a career-high ranking of 34, was appointed in January 2012 and helped oversee an increase in prize money at grand slam tournaments and a streamlining of the men's calendar.
He announced in January that he intended to step down due to his battle with the neurological disease and died at his home in Sydney.
"He was always very nice to work with. Very honest and gentle," Federer said.
"For me, it was hard seeing him not be the same anymore towards the end physically.
"But we can only appreciate what he's done for us and what he did until the last moment he really possibly could. That will never go away."
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